Canadian voters are considering a sharp turn to the right, with polls showing the opposition Conservative party taking the lead in the federal election that will be held on June 28.

Two rightwing parties, the Progressive Conservatives and the Canadian Alliance, have merged under a new leader, Stephen Harper. The party has promised to cut personal taxes, scrap the Kyoto accord on global warming, dramatically increase military spending and forge stronger ties with the US.

Mr Harper has exceeded expectations. His lack of charisma and personal charm hurt him as opposition leader but he seems cool and prime ministerial on the campaign trail. So far, he has managed to deflect attacks from opponents and critics who argue he would re-open a divisive debate on abortion and curtail newly won rights of Canadian homosexuals to marry. He could face more of a fight tonight, when the first of two nationally televised debates is held.

Mr Harper also proposed that Canada join the war on Iraq, despite the opposition of most Canadians and the ruling party. (Under the Liberals, Canada did not participate.) But, so far, the prospect of a Conservative government imposing a socially conservative agenda or becoming too cosy with the Americans does not seem to have frightened Canadian voters.

The Liberals, under the prime minister, Paul Martin, are campaigning on a left-of-centre platform, with modest plans to put more money into daycare and help for pensioners but without running a budgetary deficit. They have attacked Mr Harper on his position on the war in Iraq and abortion.

Polls show most Canadians agree with the Liberal stance on these and other issues, but the party's problem is that such support may not be sufficient for it to retain power. The most recent polling puts support for the Liberals at 30%, four points behind the Conservatives. That is a dramatic drop from the almost 50% support enjoyed by Mr Martin at the beginning of the year, shortly after he took over from the former prime minister Jean Chrétien as leader of his party and the country.

Mr Martin has been hurt by a scandal over millions of wasted government dollars and by his own performance. He does not exude the confidence he did in his years as finance minister under Mr Chrétien, when he was the heir apparent waiting impatiently for his chance. At 65, he can look tired and grey and is often caught stammering on camera. Unlike Mr Chrétien, who won three majority governments in a row beginning in 1993, he is not facing a divided opposition.

Despite their lack of enthusiasm for many of the opposition's policies, Canadian voters appear anxious for change after three terms of Liberal rule. Senior strategists for the party that has governed for 73 of the past 103 years acknowledge the Liberals are in a spiral and could lose power.

The Conservatives are gaining momentum and the Liberals are losing it, but the polls remain extremely close. With two weeks to go, either party could still win. A large majority of Canadians believe the Liberals will pull it off.

However, as the polls now stand, neither party has enough support to win a majority government. Should the Conservatives win the most seats on election night, they will likely need the support of the separatist Bloc Québécois (BQ), which is poised to sweep the mainly French-speaking province of Québéc. The bloc is some way to the left of the Conservatives and would certainly veto any move to the right on social issues. But BQ MPs would be open to the Conservatives' plan of transferring more power to the provinces.

In a minority position, the Liberals would probably turn for support to the New Democratic party, which polls suggest will attract between 16% and 19% of the national vote. But the Liberals might also have to seek support from the separatist BQ.

Either way, the result would be an unstable government, unable to hold on to power. Canadians could find themselves facing another federal election within months.